micro test 3 Flashcards
a generation is a
doubling of the population
the – creates 2 cellular compartments during binary fission
septum
– have the same activity as lysozyme and break down glycosidic bonds in peptidoglycan at the point of new synthesis
autolysins
– is highly hydrophobic and shuttles precursors across the membrane.
bactoprenol
– interacts with assembly proteins to catalyze incorporation of new sugars (glycosidic bonds)
bactoprenol
peptidoglycan transpeptidase catalyzes
cross linking
penicillin targets –
peptidoglycan transpeptidase
a long doubling time means a – growth rate
slow
every time there is a 1000 fold increase in cell populations, there has been around — generations
10
exponential growth equation
N=N0 * 2^n
generation time equation
g= t/n
in the exponential growth equation, what does N mean
number of cells at a given time
in the exponential growth equation, what does N0 mean
starting number of cells
in the exponential growth equation, what does n mean
the number of generations
in the generation time equation, what does g mean
generation time
in the generation time equation, what does t mean
time
in the generation time equation, what does n mean
number of generations
what equation can be used to determine generation time from the slope of a line
g= log2/ slope
how can division rate be calculated from generation time
1/g= division rate
what is the log of 10^8
8
what is the log of 100
2
what is 1/log(2)
3.3
? = 3.3(logN - logN0)
n
– is the phase where the bacteria is not yet in the exponential phase
lag phase
– is the phase with exponential growth
exponential
– is the phase where the bacteria have run out of nutrients and can no longer grow, but are still viable
stationary phase
– phase is when the bacteria can no longer grow and are not viable
death
chemostats can control bacterial growth rate through control of nutrient —
supply
chemostats can control bacterial cell density through control of nutrient —
concentration
if the – is too fast, washout will occur
dilution rate
a – supplies a constant supply of cells in a stable, unvarying condition
chemostat
do you have to use pure cultures in a chemostat
no
total cell counts and viable cell counts are both – measurements
direct
turbidimetric measurements are – measurements
indirect
direct cell counts are hard with – cells
motile
what is the great plate count anamoly
the number of viable cells is lower than it should be
why use CFU instead of cell in pour plates
not every cell gives rise to a colony
temperature at which enzymatic reactions occur at maximal possible rate
optimum
temperature at which membrane gells; transport processes are so slow that growth cannot occur
minimum
temperature at which proteins denature; collapse of the cytoplasmic membrane; thermal lysis
maximum
organisms that prefer temperatures around 4 degrees C
psychrophile
organisms that prefer temperatures around 39 degrees C
mesophile
organisms that prefer temperatures around 60 degrees C
thermophile
organisms that prefer temperatures around 88 degrees C
hyperthermophile
organisms that can grow at <5 degrees C but prefer temperatures around 20-40 degrees C
psychrotolerant
– organisms tend to have more alpha helices and less beta sheets
psychrophilic
– organisms tend to have more polar side chains and fewer weak interactions
psychrophilic
— organisms tend to have more unsaturated lipids in the membrane
psychrophilic
cryoprotective molecules reduce dehydration and – formation
ice crystal
– proteins tend to be less heat tolerant than thermophilic proteins
photosynthetic
prokaryotes have – temperature growth abilities than eukaryotes
higher
the – branch contains the most thermophilic and hyperthermophilic species
archaeal
non-phototrophs can exceed phototrophs in — growth abilities
thermophilic
— organisms tend to have amino acid substitutions at key places to increase stability
thermophilic
– organisms tend to have more ionic bonds and denser hydrophobic protein cores
thermophilic
some — organisms have phospholipid monolayers (archaea)
thermophilic
— organisms tend to have high saturation rates of fatty acids in their membranes
thermophilic
PCR uses Taq polymerase because it is from a — organism
thermophilic
— grow at low pH
acidophiles
— grows at high pH
alkaliphiles
– are necessary inside the cell to draw in water and to maintain a positive water balance
solutes
– require O2 for growth; O2 is the final e- acceptor in their respiration
obligate aerobes
– do not need or use O2. O2 is toxic to these organisms. these organisms ferment or respire without O2
obligate anaerobes
– organisms that can switch between aeobic and anaerobic respiration
facultative anaerobes
— require some oxygen yet atmospheric levels are toxic
microaerophiles
— bacteria with an exclusively fermentative type of metabolism but they are insensitive to O2
aerotolerant anaerobes
O2 + e- =
superoxide, toxic
O2- + e- =
H2O2, toxic
H2O2 + e- =
OH + radical
OH (+ radical) + e- =
H2O
what enzyme: H2O2 + H2O2 -> 2 H2O + O2
catalase
what enzyme: H2O2 + NADH + H+ -> 2 H2O + NAD+
peroxidase
O2- + O2- + 2H+ -> H2O2 + O2
superoxide dismutase
O2- + 2H+ + cyt c(reduced) -> H2O2 + cyt c(oxidized)
superoxide reductase
— is the positive reaction from the catalase test
bubbling
– is the most widely used method of sterilization
heat
— must eliminate the most heat resistant organisms, usually bacterial endospores
sterilization
— does not sterilize liquids but reduces microbial load (prevents spoilage)
pastuerization
— amount of time at a temperature that it takes cells to decrease in viability by 10%
decimal reduction time
– use steam to sterilize things
autoclave
is pastuerization a sterilization technique
no
– radiation causes surface decontamination
UV
– radiation generates highly reactive ions
ionizing
lethal dose of ionizing radiation for humans (grays)
10
– filters filter air and have a fibrous nature
depth
– filters have ~80% open pores and traps filtrate on the surface; common for heat sensitive liquid filtration
standard membrane
— filters are formed by etching polycarbonate film after nuclear radiation
nucleopore membrane
the amount of radiation to be applied to reduce the viable cell numbers by a factor of 10^12
lethal dose
– agents kill bacteria
bactericidal
– agents stop bacteria from growing
bacteriostatic
– agents kill bacteria and lyses them open
bacteriolytic
gaseous infusion of chemicals; no living tissue left
sterilant
kill most organisms (not endospores); cationic detergents
disinfectants
reduce microbial populations to “safe” levels; chlorine and iodine compounds
sanitizer
safe for application to living tissue; alcohol solutions
antiseptics
what is the folic acid analog
sulfanilamide
naturally occurring substances with antibacterial properties
antibiotics
— can make bacteria resistant to penicillin
beta-lactamase
attacks DNA gyrase
quinolones; ciprofloxacin
attacks RNA pol
rifampin
attacks cell wall synthesis
penicillins
attacks 50S protein synthesis
erythromycin
attacks 30S protein synthesis
tetracyclines
the range of species for which an antibiotic is effective
antibiotic spectrum
effect of a combination of antibiotics is greater than the sum of either antibiotic separately
antibiotic synergism
interference of efficacy of one antibiotic when coupled with a second antibiotic
antibiotic antagonism
resistance: if the target changes so the antimicrobial cannot interact
target modification
resistance: if the cell can pump out the antibiotic
antibiotic efflux
resistance: if the antibiotics are broken down or modified so they cannot work
antibiotic modification
resistance: cells will get a nutrient that they need that they can no longer make
resistant pathways
resistance: antibiotics cannot enter the cell
antibiotic impermeability
when something is toxic to only a certain type of cells (non-human)
selective toxicity
– are genetic elements with an obligate intracellular replication cycle
viruses
— are the extracellular form which include the nucleic acid and normally a protein coat and possibly an outer envelope
virion
classes of viruses:
ss DNA, ds DNA, ss RNA, ds RNA, ss RNA -> DNA, ds DNA -> RNA
in viruses, the nucleic acid is surrounded by a protein coat called the —
capsid
capsids are made up of one or more protein subunits called
capsomers
enveloped virus membranes are derived from —
host cell membrane
can viruses have enzymatic activity away from the host cell
no
viruses of eukaryotes can be grown in –
tissue culture
– are typically grown as plaques on lawns of cells
bacteriophage
– refers to the fact that normally only a small portion of the virions result in plaques
plating efficiency
